Obama’s Illegal Guantanamo Power Play

Two days after terrorists rampaged in Paris, the Obama administration announced that it had transferred five prisoners—including a former Osama bin Laden bodyguard—from the U.S. prison facility at Guantanamo Bay, Cuba, to the United Arab Emirates.

In the past several days, the White House has signaled that a more significant step is coming soon: the complete shutdown of the facility and the transfer of the remaining detainees—there are 107 at the moment—to sites on the U.S. mainland. Obama-administration surrogates say the president will effect the change by using his favorite tool, an executive order. But this would be utterly illegal, since Congress has specifically prohibited the transfer of Guantanamo detainees to U.S. soil.

Although the president’s war powers are broad and formidable, so are those of Congress. In particular, the Constitution specifically vests the legislative branch with the powers to “declare War”; to “raise and support Armies”; to “make Rules concerning Captures on Land and Water”; to “make Rules for the Government and Regulation of the land and naval Forces”; and to appropriate funds for all of these purposes.

This language provides Congress with the authority to determine where enemy detainees may be held. In addition, the constitutional provisions that give the legislature the authority to regulate foreign commerce and establish uniform rules of naturalization also empower it to control the borders and regulate access to the U.S.

As Supreme Court Justice Robert Jackson explained in a 1952 case involving President Truman’s ill-fated and unlawful seizure of the nation’s steel mills: “When the President takes measures incompatible with the expressed or implied will of Congress, his power is at its lowest ebb, for then he can rely only upon his own constitutional powers minus any constitutional powers of Congress.”

In fact, the Supreme Court has already rejected the notion that the president alone has plenary authority over detained enemy combatants. In Hamdan v. Rumsfeld (2006), justices struck down presidential use of military commissions to try Guantanamo detainees, concluding that those commissions did not fully comport with requirements adopted by Congress in the Uniform Code of Military Justice. As the majority wrote: “Whether or not the President has independent power . . . to convene military commissions, he many not disregard limitations that Congress has, in proper exercise of its own war powers, placed on his powers.”

In the exercise of their respective war powers, both Congress and the president must respect the other’s legitimate authority. This often means that Congress will have the final say on whether a given war is waged and for how long; the president determines how the conflict is managed. Such a division of power is both consistent with the Constitution and historical practice and has the added virtue of fostering accountability.

Neither Congress nor the president should make it impossible for the other to carry out its constitutional functions. But no such circumstance is presented here. Congress has not impeded the president’s ability to capture and hold enemy combatants. It has simply determined that he must hold them outside of the U.S.

What Congress has, in fact, done is simply made it impossible for the president to keep a 2008 campaign promise in the way that he would like. This does nothing more than present a political problem for Mr. Obama. It does not trench upon his constitutional authority.

Similarly, that the president considers negative foreign opinion about Guantanamo to be a “national security threat” cannot expand his constitutional authority at Congress’s expense. If that were the case, then the military commissions in Hamdan v. Rumsfeld would have been upheld. There is little doubt President Bush believed that national security required the use of military commissions, configured as he saw fit, at Guantanamo. This cut no ice with the Supreme Court.

The ban on bringing Guantanamo detainees to the U.S. has been included with past annual defense-authorization bills and is a provision in legislation Mr. Obama recently signed, while indicating in his signing statement that the ban is unconstitutional and therefore nonbinding.

The president is wrong. Although Congress cannot use its power of the purse to achieve an end otherwise forbidden to it, in this instance lawmakers are exercising their rightful authority—both under the “captures” clause and the “military regulations” clause, as well as the Constitution’s provisions giving them control over American borders.

Congress should follow the recent suggestion by Sen. John McCain and sue the president—as it has in other matters—and ask the courts to bring Mr. Obama back within the lawful bounds of his office.

Messrs. Rivkin and Casey are constitutional lawyers and served in the Justice Department under Presidents Reagan and George H.W. Bush.